Persistent contaminants of emerging concern in a great lakes urban-dominant watershed

Within the Great Lakes, contaminants of emerging concern (CECs) have been detected in urban surface waters. Understanding the human and ecological health consequences of environmentally-relevant exposures to persistent CECs, particularly as complex mixtures, is essential. Surface water and a limited number of sediment samples were collected over two years (Spring and Fall 2018–2019) at multiple locations in the Lake Huron to Lake Erie corridor to investigate more than 150 CECs. Surface water was analyzed for pharmaceutical and personal care products (PPCPs), pesticides, and per- and polyfluoroalkyl substances (PFAS). Sediment was analyzed for PFAS. Fifty compounds were detected at ng/L or ng/kg levels. Synthetic sweeteners accounted for 55.7% of the cumulative concentration of all compounds detected across sampling events, followed by pesticides (27.5%), pharmaceuticals (11.7%), and stimulants (3.5%), with 14 compounds consistently detected: acesulfame-potassium, sucralose, sulfamethoxazole, acetaminophen, lidocaine, atenolol, gemfibrozil, iohexol, atrazine, diaminochlorotriazine, deethyl-atrazine, deisopropylatrazine, 2,4-Dichlorophenoxyacetic acid, and caffeine. Compound mixtures became increasingly complex downstream and indicated that the downstream Lake Huron to Erie corridor is wastewater effluent-dominated, whereas the aquatic environment associated with Lake St. Clair is influenced by a mixed urban, suburban, and agricultural landscape. These results will inform follow-up studies on persistent contaminant mixtures and multiple stressors, and offer science-based priorities and evaluation objectives for natural resource and public health agencies/initiatives.